"Nobody likes delays," he said. "They want to bring the planes closer and increase traffic flow." To this day, the FAA says it regularly receives proposals from airline carriers, manufacturers and airports to increase the number of passengers they handle by decreasing space requirements.

According to the FAA, an average delay of 10 minutes per flight at an airport the size of Seattle-Tacoma International results in a combined $93 million in losses for the airline carriers.

In 1991, according to an FAA report, 23 of the nation's largest airports each suffered more than $32 million in losses, solely because of delays, many of which occurred because the approach routes to those destinations were packed with planes. The problem is limited navigable airspace. Every airline wants to be in it during convenient flying hours, from dawn to dusk.

Any lengthening of distance requirements between aircraft makes for fewer flights and fewer opportunities for takeoffs and landings during optimal flying times.

"They'll never say it, but the FAA is in the business of keeping aircraft moving," said pilot Peter Murray, who has flown commercial jets for 28 years and regularly skippers 757s. "It basically comes down to dollars and cents."

All of which makes hard-hit airline carriers more interested in reducing airplane separation standards, which would allow them to land more planes more frequently and would improve their bottom lines.

In fact, said John O'Brien of the Air Line Pilots Assn., which often finds itself fighting for increased space between aircraft for safety reasons, "we see much more interest in doing these things when people are looking for a way to better themselves economically."

The FAA acknowledges that there is a direct correlation between the lack of navigable airspace and aircraft separation requirements, and it is an area of concern to the FAA and the entire industry, spokesman O'Donnell said. Listed among the goals of the FAA's 1991 annual report on the airport capacity problem: "More efficient spacing along the final approach path."

"The FAA's position is that there is insufficient capacity in this country to meet the projected needs," O'Donnell said.

Even though the FAA recently has taken actions that suggest the 757 could be reclassified as a heavy jet, which could require up to two miles of increased spacing--from four miles to six--for smaller trailing aircraft, the agency strongly asserted that it did not sacrifice safety by ignoring the data it had received.

However, it was with no information other than the two recent crashes that prompted FAA Administrator David Hinson to issue a bulletin Dec. 22, instructing the nation's air traffic controllers to tell pilots landing behind 757s they should be aware of potentially heavy turbulence.

O'Donnell said the agency would never compromise the traveling public or the "public that lives under the flight path." But, he said, "we do recognize that certain orders will have a definite economic impact. . . . We have to ask: 'Will this create an economic hardship that will destroy the industry?' "

Although the FAA looks out for airline manufacturers and carriers, O'Donnell said, the agency does not shirk from taking a tough stand. He referred to the Noise and Capacity Act of 1991, which requires the industry by 2000 to phase out older models such as 727s, 747s and DC-9s in favor of quieter, more fuel-efficient, twin-engine aircraft such as the 757, 767 and the new 777.

O'Donnell said: "The airline industry did not like it. They maintained that it would force many of them out of business. Nevertheless, we felt there was a need to do that, and we did it."

For its part, Boeing spokeswoman Elizabeth Reese said, the company would need to examine closely any proposal to increase separation distances for the 757. In addition to the concern about increased delays, Reese said, there is another complication: Many environmentally sensitive airports, such as John Wayne in Orange County, bar aircraft classified as heavy. Reclassifying the 757 as a heavy would probably make the aircraft builder's third-most popular jet less marketable, experts say.

"Slots are few and airports are real crowded," Reese said. "You try to get the airplanes in and out as fast as you can."

At a minimum, aviation sources say, even if the FAA did not want to adopt stricter spacing requirements when it first learned of the 757's wake turbulence problem, it was obliged to alert pilots so they could take extra precautions.

Murray, the commercial jet pilot, said air traffic controllers are very busy and frequently encourage pilots to fly under visual flight rules, which takes much of the responsibility for maintaining a safe distance between aircraft off the controller's shoulders.

"It's obvious with this wake vortex problem you can't just tell a small-plane pilot: 'There's a Boeing 757 in front of you, good luck. You're on your own.'